


The Last Straw

by Dragoncurl



Category: Undertale (Video Game)
Genre: M/M, also no ecto dicks here folks, how the hell did this get so freaking long jesus christ, just some nice petting for the bones and the soul, unless you count grillbys
Language: English
Status: Completed
Published: 2017-05-22
Updated: 2017-05-22
Packaged: 2018-11-03 15:34:00
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,428
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10970211
Author URL: https://archiveofourown.org/users/Dragoncurl/pseuds/Dragoncurl
Summary: Grillby has endured Sans' tab for a long time without a single word of protest.That's about to change.





	The Last Straw

**Author's Note:**

> welp i wrote this instead of working on my next fic and its fucking almost 4.5k long what the fuck
> 
> enjoy some fiery boning i guess

Sometimes, Grillby feels as though he should be congratulated for having such fine control over his emotions and, by extension, his flames. Fire elementals like himself are notorious for being quick to anger, some quirk of their essence or other, but the bartender? He's always had flawless self-control.

Or so he tells himself, anyway.

"hey grillbz, im plannin' a party here at the bar, doggo just got accepted as a sentry. yer cool with that, right?"

The question breaks through Grillby's concentration like a rock through a glass roof. The bartender's bespectacled gaze finds Sans, and the falling shards must show on his face because the skeleton's ever-present grin wavers for just a moment.

"just put it on my tab, yeah?"

Grillby doesn't look away. His hands are still around the glass and rag. He holds the skeleton's gaze for several seconds, unmoving, and with every tick of the clock the skeleton's grin wavers more, until finally the elemental breaks eye contact and he can almost hear Sans slump forward in relief again.

But he's not off the hook yet. Grillby sets down the glass and rag and paces away. He holds the fire exit open and looks back at Sans without a word. After a moment, the skeleton chuckles and slides off his seat.

"y'wanna help plan the party? we could throw in a couple sparklers for ya."

The skeleton walks past the flame, into the kitchen area. Grillby shuts the door behind him, then steps around Sans and opens the door to his own living area in the back of the bar. Grillby offers no explanation when Sans' grin fades. He just waits.

Eventually the skeleton complies, shrugging and putting his smile back on, but the elemental can see a very slight tension across Sans' shoulders.

"alright, no problem with gettin' cozy to talk it over."

Once again, Grillby shuts the door behind them. This time, he locks it. The click seems abnormally loud in the quietude of the back room, and it makes Sans stop in his tracks and look back over his shoulder.

Grillby just steps around him again and goes to the center of the room, navigating around the furniture, all dark polished woods and dark warm tones on the walls and fabrics. The elemental stops next to the coffee table and indicates one of the armchairs with a hand, and waits.

"uh, alright. this is gettin' kinda weird, grillbz, just sayin'."

Despite his words, Sans complies again. It takes some work for him to climb onto the plushy armchair, but after a few moments he's comfortably seated, feet hanging off the edge and well away from the floor.

Leaving Sans in the armchair, Grillby turns away and walks to a desk by the wall. He pulls a pad and pen out, then writes a number across the paper, tears it off the spiral, and goes back to the skeleton to hand him the note. Sans takes it and reads the number, but then just looks up at Grillby in confusion.

"That is your current tab."

Sans' eye sockets widen. He opens his jaw to speak, but nothing comes out.

It's Grillby who puts his hands on the arms of the chair and leans down, so close the skeleton cringes back. His flames are burning brighter, higher, hissing and popping quietly, and his eyes narrow behind his glasses.

"And yet you want to throw a party in _my_ bar, when you know how I feel about parties."

Sans doesn't dare speak. He doesn't even move.

"I am **tired** ," a particularly loud crackle accompanies the word, "of putting up with your _tab_ silently."

Grillby almost spits out the three-letter word like it's acid on his tongue.

Sans isn't smiling. He suddenly feels distinctly small, sitting in an overlarge chair, with the fire monster looming over him, the heat that is usually so well controlled seeping through his hoodie, soaking into his bones.

"i-i don't got that kinda money, grillbz, ya know i d-"

He's cut off by Grillby's hand closing over his mouth. Sans can't contain a slight whimper as the searing flames lick across his cheekbones and just barely under his eye sockets, way too close to his eye lights for comfort.

"I. Don't. _Care_ . You **will** pay your tab, one way or the other."

Grillby releases the skeleton's jaw, but doesn't move away. Sans is still shrunken in on himself, trying to sink into the armchair and away from the stinging heat emanating from the elemental.

"u-uh. i could, uh, w-work here a while?"

It's such a hollow offer Grillby doesn't even dignify it with a response. They both know that wouldn't solve the problem. Sans' near-constant presence in the bar instead of at his various sentry posts is a testament to his nonexistent work ethic. The skeleton has begun to sweat, eye lights darting this way and that as if trying to find some gap to escape through, but Grillby's just too close, too _big_.

"i-i... uh..."

Sans is desperately trying to think of something that can get him out of Grillby's sun-like presence, but then...

A smile splits the elemental's mostly featureless face. A jagged grin that, seen up close like this, sends a ripple of cold, icy fear down Sans' spine. Grillby's stinging hold grabs his jaw again and he tenses up, but this time, the flaming fingers are on either side of the bone, and the palm is propping up his chin, and then Sans' vision is almost completely filled with light and heat as the elemental leans in further and his fiery mouth finds the skeleton's.

Sans freezes. Metaphorically, of course. He's actually burning up inside his own clothes.

Grillby likes control. He likes keeping things nice and tidy in his bar. He always washes the dishes diligently at the end of every day, and takes out the trash to burn it after closing time, and keeps both the bar and kitchen and his living space spotless. Sans is suddenly very painfully aware of this, in a rather literal way with the elemental's searing lips against his.

Should he resist? Should he try to pull away? Maybe shove Grillby off him with blue magic? Take a shortcut? It's his first instinct, but...

Well.

Sans would be lying if he said that, obvious pun aside, Grillby looks fucking smoking _hot_. Just... something about the way he dresses? Sans isn't really sure why exactly, but damn if the guy isn't a sight for sore eye sockets. It's not hard to see the muscles under his dress shirt and vest whenever the bartender moves or mixes up a fancy drink, and the way he can juggle bottles while preparing cocktails is just fascinating. He's a pretty big reason why Sans spends so much time at the bar shirking work.

Maybe...

Maybe this isn't so bad?

All of this flies across the skeleton's skull in the blink of an eye, and then he feels himself relaxing under the waves of Grillby's heat, and probing forward with a summoned blue tongue, and letting his eye sockets slide shut.

Grillby's response is a hiss of fire, like flames doused in a light splash.

His own lava-like tongue meets the skeleton's, and Sans flinches, it's almost too hot to touch, a sharp sting races across his mouth. But after the initial impact there's only a dull ache left that is... actually kind of nice? It seems to make his conjured tongue all the more sensitive, and when Grillby pushes forward Sans pushes back, even though the elemental's grip is still firmly around the bottom of his jaw. Neither of them strictly _needs_ to breathe, so it doesn't take long for them to be lost in each other's mouths, flaming tongue exploring flat, square teeth, blue counterpart tracing sharp, heated fangs.

That is, until Sans moves a hand forward and his fingers brush along Grillby's front, trying to blindly reach his bowtie.

The elemental's grip suddenly shifts, leaving Sans' jaw only to close tightly around his wrist. The skeleton yelps with the fresh sting, and the makeout ends. Grillby has pulled back and is staring him down with a dangerous look.

"s-sorry?"

The flame's smile feels way too morbidly amused for comfort.

"You're paying your tab, Sans."

The grip around the skeleton's arm tightens. Grillby can feel the bone creak under his fingers. Sans tenses up again.

"You will do as I say, understood?"

Grillby holds the pressure stable. Sans doesn't dare try to pull away. He doesn't even look down.

"y-yeah, sure thing, grillb. just gotta play dead, huh? pretty eas-"

He's cut off again, this time by a single flaming finger across his mouth. It doesn't even touch him, but the heat is still strong enough to sting.

"You will speak only when I tell you to."

The fingers stays in place. Sans opens his mouth, then hesitates, closes it, and nods instead. Grillby smiles in satisfaction and, finally, straightens himself, letting Sans breathe a sigh of relief. But he doesn't have much time to relax. The elemental points to a spot just a few paces away, between the coffee table and a wide, sumptuous couch colored a dark maroon.

"Stand here."

Sans takes a moment to force some steadiness into his knees; apparently being bossed around by Grillby is _really fucking hot_. He'd would've never expected something like this, but now there's no denying it. Once the skeleton slides himself out of the armchair he tries to keep his breathing under control as he walks past Grillby, stops on the indicated spot, and turns to face the elemental.

The bartender grins. Sans is blushing furiously. There's a bright vibrant blue painting his bone from cheekbone to cheekbone. He's not meeting Grillby's gaze, so he doesn't see the elemental fold his arms.

"You're enjoying this, aren't you?"

Sans doesn't speak. He somehow manages to blush harder instead.

"Answer me. _Truthfully_."

The skeleton's fists clench. He's still not looking at Grillby. He'd probably gulp down nervously if he had a throat.

"y-yeah."

It seems impossible for that azure blush to spread further, and yet it does. Sans' hands twitch like they want to reach up and yank his hood over his face, but he has enough sense not to do it. Grillby's still grinning in morbid amusement. He just pivots on the spot and sinks into the armchair Sans was just occupying. And because they're alone and Sans looks about ready to spontaneously combust, he leaves his legs wide open, just to give Sans something nice to look at.

The skeleton's eye lights zero in on Grillby's clothed crotch before he catches himself and wrenches his gaze elsewhere. The elemental just chuckles.

"Strip."

That makes Sans' eyes whiplash back to Grillby's face in disbelief.

"Slowly."

For a few seconds, Sans can't believe the ears he doesn't really have. He actually opens his mouth to argue, but stops himself. He hesitates. Grillby's just sitting there like _that_ , waiting, one hand curled on the side of his face, the other resting on the arm of the chair, that thin little smirk splitting the normally flat surface of his face. And, in some small twisted way, Sans finds himself wanting to do it.

He just has no idea how.

The skeleton starts by reaching up for his zipper and pulling it down slowly. Grillby's eyes follow the motion. Sans slides the hoodie off his shoulder, keeping his movements slow and smooth. He straightens his arms and holds them back, letting the hoodie slide down until he catches it in his fingers for just a moment before it piles on the floor. Grillby is alternating between watching Sans' hands and meeting his eye lights. Sans inevitably looks away when he does, but he can't help looking back to gauge the elemental's reaction.

The skeleton takes a steadying breath, and keeps going.

He grabs the bottom hem of his shirt and pulls it up slowly. The fabric obscures his vision as he tugs it over his head, but he can still see Grillby's light as a white haze through it. He yanks the collar free over his skull, and also lets the shirt slide down one arm, catch on his curled fingers, and pile on the floor. The bartender is burning a much brighter shade now, a pale blue core under an yellow-white surface to his flames. Even standing a few paces again, and especially with his ribs all bare, he can feel the heat radiating off Grillby in waves, washing over him, racing through his bones like static, pooling in a gut he doesn't have.

Sans can't help a slight gasp, but he continues.

His hands find the strings of his shorts. He undoes the messy knot and lets them hang free, and of course the thing sags under its own weight, letting the wings of his pelvis peek into view. Sans hooks his thumb under the band and tugs it wider a little, enough that holding one side steady makes the other drop and form an angle. He lets go and feels the garment pool around his ankles, then steps out of it and nudges it under the coffee table. He's painfully aware he's not really doing much, this isn't a sexy strip, but Grillby doesn't show any sign of disliking it.

The last step ( _heh_ ) is to worm his way out of his shoes and socks, which is easy since the former are always untied and the latter are oversized, and then Sans is standing naked in Grillby's bedroom/office/whatever the hell he calls it, and feeling immensely exposed. He resists the urge to hug himself protectively though. The skeleton just stands there and waits.

Grillby's eyes go up and down Sans' frame several time. His bones are thick, much thicker than any human's, and he can actually see some of the gaps between them, especially on the vertebrae of his lumbar. There's no cartilage between the bones, just air and unseen energy. It's rather fascinating, really. And there's a shimmer of white inside his ribcage, it looks like he's trying to keep his soul from manifesting.

That won't last long.

"Lie down on the couch."

Sans draws in a shallow breath before complying. It's only when the skeleton is lying flat that Grillby finally gets to his feet again, and starts undoing his bow tie.

"Arms above your head."

Again, Sans obeys silently. He just watches with an air of slightly uneasy anticipation as Grillby steps close, twirling the undone bowtie around his fingers.

"Clench your fists together and lift your head."

Sans does so. With his wrists flush against one another, Grillby leans down and wraps the bow tie around them, tying it securely. Then, with a very obvious grin, he yanks the skeleton's hands down behind his skull, all the way down to his neck, forcing his arms to bend tight and drawing a surprised gasp from Sans' jaws. Grillby deftly ties the remainder of the bow tie around the skeleton's neck, even going so far as to redo the bow neatly before straightening himself to examine the result.

Sans now has his arms bent on either side of his head with little to no room for movement, and his hands tied behind his neck, and the black bow just under his jaw making him look like a wrapped-up present.

A gasp escapes the skeleton. He's staring back at Grillby in disbelief, but this time it's the good kind.

The bartender just turns away and starts undressing. While he unbuttons his vest, he nudges the rest of Sans' clothes under the coffee table. The vest is folded neatly and set down on top of it, and the dress shirt follow shortly after. Then, Grillby unbuckles his belt and makes a point of sliding it out of its hoops, rolling it up, and setting it aside before unbuttoning and unzipping his pants. As he bends down Grillby glances back and catches Sans very clearly staring, he's so focused he doesn't even notice Grillby looking at him. While he's bent almost double, the elemental wedges his shoes and socks off, and only then steps out of his pants, folds them up, and sets them down atop the rest of his clothes. His glasses sit on top of everything else.

"Close your eyes."

He hasn't turned around yet. Grillby just glances over his shoulder and waits for Sans to comply, which he does after a momentary, unspoken complaint.

"Spread your legs."

Grillby hears more than sees Sans obey. By the time he turns around one of the skeleton's legs is hanging off the edge of the couch, and the other is bent and propped up against the back of it. The bartender settles between them, hands on either femur to maneuver Sans' legs over his own as his thighs frame the skeleton's hips.

"Keep your eyes and mouth shut."

The flaming fingers trail up the leg bones and find the pelvis, stroking across the bare bone, feeling the dips and curves, tracing the edges of the holes at the front, sliding the palms fully around the curved inside.

A heavy shiver rattles up Sans' frame. He only lets a slight whimper pass his teeth, but he's clearly straining against the bow tie, his chest starts spasming with heavy breaths and gasps, his hips actually buck up into Grillby's touch, he just can't help it. It _hurts_ , it's way too hot, but it's so _good_ at the same time, and he can't stop it, his soul forms inside his ribs, glowing brightly with bliss.

Grillby just grins to himself. His fingers trail along to the outside of Sans' pelvis again, feeling around the head of his femurs before starting to move up, to trace the curve of each wing of the pelvic bone. The sizzling fingers move on and wrap carefully around the spine and star dancing along each curved edge, trying to dip between the cylindrical bones, moving lower and investigating the blunt messy spurs along Sans' back, traveling slowly up toward his chest.

Sans can only breathe and squirm. His breaths are hissing through his teeth in the effort not to cry out, and he's squeezing his eye sockets so tight he might just crack the bone. Every now and then a little broken noise slips past his teeth, a half-formed vowel, and unfinished syllable, things like that. Grillby's light in unrivaled, filling the entire room, but Sans' little soul is starting to make a valiant effort to match it.

The elemental continues to explore. His fingers reach the bottom-most pair of ribs, the only one with floating ends, and he follows the entire length of each all the way to the tip before going back inward. Then, he starts tracing each curved bone, going up along the outside of one, then going back down along the next, all the way up to Sans' collarbones. These too have their lengths stroked up and down. And finally, Grillby's hands follow Sans' sternum back down, and start stroking the inside of his ribs, but still avoiding the skeleton's shining heart.

Sans can barely think. His whole body feels like it's on fire, which as far as he knows might actually be true; Grillby could probably engulf him in flames without taking off even the slightest fraction off his HP. Every touch stings and leaves a sharp ache behind that fades very, very slowly, and yet it feels so fucking _great_ and he wants so badly to _beg_ Grillby to do it to his soul already and just _get this over with_ and he _can't_ and it's driving him **_mad._ **

But the bartender is close. So very close. His fingers are wandering all around the inside of Sans' ribcage, his knuckles sometimes just _barely_ miss touching the soul as his fingertips slide along the sensitive inside of the ribs, the sternum, the spine. As one last touch, Grillby pulls one hand back and walks it along the sternum, all the way up to Sans' mouth, and he doesn't even need to ask to make Sans slacken his jaw. Grillby's thumb presses against Sans' blue tongue and he presses back, and he actually clasps his lips around it and _sucks on it_.

It's the first time Grillby allows himself the slightest of gasps.

His response is to finally, at long last, close his fingers around Sans' soul and engulf it in flames, and the reaction is exactly what he was hoping for.

The skeleton's jaw suddenly flies open and every sound he'd been holding back _explodes_ out of him in a single raw scream that a natural fleshy throat would probably not be capable of. His whole body seizes up, his soul shines bright enough to actually force Grillby to look away, and for a few seconds he's completely lost, caught up in a firestorm of nearly equal parts agony and pleasure that completely clogs up his skull.

Eventually, the skeleton just collapses. His chest is heaving like he's just run a marathon. His soul dissipates from between Grillby's fingers and vanishes. He just lays there, utterly spent, eye sockets half-lidded but completely dark.

Grillby himself is breathing hard just from watching.

But he's not done yet. Literally

He clacks Sans' jaw shut with the back of his fingers, which is enough to draw the skeleton's attention. Or as much of it as he can muster, anyway.

"mmhhhwuh?"

"I didn't say you could speak or open your eyes yet."

That cuts through the haze of whatever magic passes for endorphins in Sans' skull. He tenses up a little again and hesitates, but it's not like he's in any position to argue. The skeleton just screws his eye sockets shut again, though he can't really stop his noisy breaths. Thankfully Grillby doesn't seem to mind.

The elemental maneuvers Sans' legs instead so he can crawl forward and rise onto his knees, towering higher over Sans' waist. He's still breathing hard when his hand closes tight around one of the skeleton's upper arms and yanks him sitting. Grillby's other hand molds itself to the back of Sans' skull, and suddenly there's something pressing against his teeth, and he knows exactly what it is.

The skeleton lets it in with barely a moment's hesitation. He feels the stinging heat on his tongue as he starts to work the conjured muscle around the volume even though Grillby doesn't stay still.

The bartender starts moving quickly, speeding up too fast for Sans to ever keep up without his sight, and it's all he can do to keep his jaw wide open and his tongue in a place Grillby can feel, and he can hear the elemental's fire flaring, sizzling and popping and crackling, it's hard to tell if it's his quiet voice or just his flames.

It's over just as quickly as it started.

Grillby works himself up to a frenzy, grunts, shoves himself as deep as Sans' mouth cavity will allow, and fills it with something that feels like magma.

Bluish tears inevitably spring up in the skeleton's sockets from the sheer heat of it, and when he's finally released after gulping down he actually coughs and smells smoke wafting through his teeth.

He dares a peek up at Grillby and finds him propping himself up heavily on the back of the couch, panting, and then their eyes meet and Sans freezes, still squinting.

The elemental just chuckles smoothly and undoes the bow tie.

Sans' arms finally slump back down to his side, not without a slight wince. His elbows were actually hurting a little. He rubs his hands around them and wipes away the traces of tears while Grillby drops the bow tie atop his other clothes and sits back again.

The bartender says nothing. He's just watching Sans with a little amused smirk. Sans can only blush and avert his eyes. The silence lingers.

"I don't think this was enough to pay your tab, Sans."

The skeleton glances back with very obvious apprehension, but Grillby waves a dismissive hand.

"Don't worry. I just mean that this is going to become a regular meeting."

Sans relaxes, then blushes and rubs his arm.

"i... yeah, i guess... that's a bone i could pick with you. you're pretty hot, and... this wasn't so bad."

"You mean it was amazing."

Sans blushes harder. Grillby's still lounging there on the opposite end of the couch while his flames come back down to their regular colors, just... all naked and muscular and _hot_ and Sans is having to try very hard not to stare.

"y-yeah, i guess it was. i didn't... i had no idea i'd like that stuff. it was..."

When he looks at Grillby, his eyes immediately flicker down before he forces them to focus on the bartender's face.

"yeah, okay, it was really fucking great. just that last part that kinda got a bit much. maybe warn me next time?"

"I'll keep that in mind."

Another silence falls. Sans starts to get dressed, and Grillby follows suit shortly after. They finish at about the same time, though Sans still feels the leftover aches across his bones from the fire. His mouth feels particularly tender, he'll have to be careful with the temperature of his food for a while.

"so uh... how often are we talkin' here? 'cause i can't be doin' all that every day."

"...Every monday, starting next week. After hours, unless I bring you in earlier."

"...y'mean i might not have a warning?"

Grillby smiles knowingly.

"Is that a problem?"

Sans blushes furiously again.

"uh, n-no, i guess not. just don't go overboard with it, yeah? i still got a reputation to keep."

"No, you don't. Not with that scream."

Despite being a skeleton, Sans somehow goes pale all at once.

Grillby just smiles to himself, turns on his heel, and walks away without another word.

Back in the bar proper, all the other occupants give him inquisitive, even worried looks in some cases, but he offers no explanation. He just returns to the glass and rag he was tending to before, making sure to keep his face free of any expression whatsoever.

After a while, Sans emerges through the fire exit with his hood pulled low over his head and a blush that is impossible to miss, even in the relatively dim light of the bar.

He buries his face in his folded arms when first Doggo, then the rest of the Snowdin Canine Unit, starts to howl their approval.


End file.
